DE102018103442A1 - Angle sensor system - Google Patents

Abstract

An angle sensor system includes a magnetic field generating unit for generating a rotating magnetic field and an angle sensor for detecting the rotating magnetic field to generate a detection angle value. The rotary magnetic field includes first and second magnetic field components that are orthogonal to each other. Each of the first and second magnetic field components includes an ideal magnetic field component and an error component corresponding to the fifth harmonic of the ideal magnetic field component. The angle sensor includes first and second detection signal generating units. Each of the first and second detection signal generating units includes a magnetic layer whose magnetization direction varies according to the direction of the rotating magnetic field. The magnetic layer is provided with a magnetic anisotropy adjusted to reduce an angle error resulting from the error components of the first and second magnetic field components.

Description

BACKGROUND OF THE INVENTION

Field of the invention

The present invention relates to an angle sensor system comprising a magnetic field generating unit and an angle sensor.

Description of the Related Art

In recent years, angle sensors have been widely used in various applications, such as detecting the rotational position of a steering wheel or a servomotor in a motor vehicle. The angle sensors generate a detection angle value corresponding to an angle to be detected. Examples of the angle sensors include a magnetic angle sensor. An angle sensor system employing a magnetic angle sensor is typically provided with a magnetic field generating unit for generating a rotating magnetic field whose direction changes in response to the rotation or linear motion of an object. The magnetic field generating unit may be a magnet configured, for example, to rotate. The angle to be detected by the magnetic angle sensor corresponds, for example, to the rotational position of the magnet.

Among known magnetic angle sensors, a sensor comprising a plurality of detection circuits for generating a plurality of detection signals having different phases and generating a detection angle value by performing calculations using the plurality of detection signals, as in JP 2011 - 158488A disclosed. Each of the plurality of detection circuits comprises at least one magnetic detection element. The magnetic detection element includes, for example, a spin valve type magnetoresistive element comprising a magnetization-fixed layer whose magnetization direction is fixed, a free layer whose magnetization direction varies according to the direction of the rotary magnetic field, and a nonmagnetic layer interposed between the magnetization-fixed layer and the magnetoresistive layer free layer is located.

For the magnetic angle sensors, ideally, each of the plurality of detection signals has a waveform of a sinusoidal curve (including a sine waveform and a cosine waveform) when the angle to be detected varies with a predetermined period. However, there are cases where the waveform of each detection signal is distorted from a sinusoidal Kure. Distortion of the waveform of each detection signal may result in some error in the detection angle value. The error occurring in the detection angle value is hereinafter referred to as the angle error.

In distortion of the waveform, each detection signal includes an ideal component that varies to map an ideal sinusoidal curve and an error component that is different from the ideal component. A detection angle value calculated, each detection signal consisting only of the ideal component, corresponds to a true angle to be detected by the angle sensor. Such a detection angle value is hereinafter referred to as ideal angle. The angle error is the difference between the ideal angle and any detection angle value.

The causes of the distortion of the waveform of each detection signal are generally divided into a first cause related to the rotating magnetic field generated by the magnetic field generating unit and a second cause related to the magnetic detection element. In the case of an ideal angle sensor system, when the angle to be detected varies with a predetermined period, a waveform representing a variation in the strength of a component in a direction of the rotating magnetic field at the position of each detection circuit, hereinafter referred to as a field strength waveform, is sinusoidal, and the waveform of each detection signal generated by each detection circuit is also sinusoidal. The angle error caused by the first cause is due to the distortion of the field strength waveform versus a sinusoidal curve.

The angle error caused by the second cause is due to the distortion of the waveform of each detection signal from a sinusoidal curve even if the field strength waveform is sinusoidal. The angle error caused by the second cause also arises when, for example, the free layer of a magnetoresistive element serving as a magnetic detection element has a magnetic anisotropy. An angle error can also be caused by the combination of the first cause and the second cause.

JP 2011-158488A describes a magnetic sensor capable of reducing the angle error caused by the first cause. The magnetic sensor comprises a first detection unit and a second detection unit located at mutually different positions. The first detection unit comprises a first detection circuit, a second detection circuit, and a first calculation circuit for calculating a first detection angle on the first detection circuit Basis of output signals from the first and second detection circuits. The second detection unit comprises a third detection circuit, a fourth detection circuit, and a second calculation circuit for calculating a second detection angle on the basis of output signals from the third and fourth detection circuits. The magnetic sensor further includes a third calculation circuit for calculating a detection angle value based on the first and second detection angles.

The in JP 2011-158488A The described magnetic sensor requires a large number of detection circuits and calculation circuits that complicate the magnetic sensor in the embodiment.

PRESENTATION OF THE INVENTION

It is an object of the present invention to provide an angle sensor system which is simple in design and capable of reducing an angle error associated with a rotary magnetic field generated by a magnetic field generating unit.

An angle sensor system of the present invention includes a magnetic field generating unit and an angle sensor. The magnetic field generating unit generates a rotating magnetic field whose direction varies at a predetermined detection position according to an angle to be detected. The angle sensor detects the rotating magnetic field at the detection position and generates a detection angle value corresponding to an angle to be detected. The rotary magnetic field at the detection position includes a first magnetic field component in a first direction, and a second magnetic field component in a second direction orthogonal to the first direction.

The angle sensor includes a first detection signal generation unit, a second detection signal generation unit, and an angle detection unit. The first detection signal generating unit generates a first detection signal having a correspondence to the cosine of an angle that the direction of the rotating magnetic field forms at the detection position with respect to the first direction. The second detection signal generation unit generates a second detection signal having a correspondence to the sine of the angle which the direction of the rotation magnetic field forms at the detection position with respect to the first direction. The angle detection unit generates the detection angle value based on the first and second detection signals.

The first detection signal generation unit includes at least a first magnetic detection element. The at least one first magnetic detection element includes a first magnetic layer whose magnetization direction varies according to the direction of the rotating magnetic field at the detection position. The first magnetic layer is provided with a first magnetic anisotropy.

The second detection signal generation unit includes at least a second magnetic detection element. The at least one second magnetic detection element includes a second magnetic layer whose magnetization direction varies according to the direction of the rotational magnetic field at the detection position. The second magnetic layer is provided with a second magnetic anisotropy.

When the angle to be detected varies with a predetermined period, each of the first and second magnetic field components includes an ideal magnetic field component and a fifth harmonic magnetic field component. The ideal magnetic field component varies periodically such that it maps an ideal sinusoidal curve. The fifth harmonic magnetic field component is an error component corresponding to a fifth harmonic of the ideal magnetic field component. The fifth harmonic magnetic field component causes an error that varies with ¼ of the predetermined period in the detection angle value.

Assuming that each of the first and second magnetic field components consists only of the ideal magnetic field component when the angle to be detected varies with the predetermined period, each of the first and second detection signals includes an ideal signal component and a third harmonic signal component. The ideal signal component varies periodically such that it maps an ideal sinusoidal curve. The signal component of the third harmonic is an error component corresponding to a third harmonic of the ideal signal component. The third harmonic signal component results from the first and second magnetic anisotropies and causes an error that varies in the detection angle value by ¼ of the predetermined period.

In the angle sensor system of the present invention, the first and second magnetic anisotropies are set to allow the detection angle value to contain a reduced error varying with ¼ of the predetermined period, compared with both the error that only the fifth harmonic magnetic field component in the Causes the detection angle value as well as the error caused only by the signal component of the third harmonic in the detection angle value.

In the angle sensor system of the present invention, the error caused only by the fifth harmonic magnetic field component in the detection angle value and the error caused only by the third harmonic signal component in the detection angle value may have a phase difference of 45 °.

In the angle sensor system of the present invention, both the first and second magnetic anisotropies may be magnetic shape anisotropies. A simple axis direction established by the first magnetic anisotropy and a simple axis direction established by the second magnetic anisotropy may be orthogonal to each other.

In the angle sensor system of the present invention, when the angle to be detected varies with a predetermined period, each of the first and second magnetic field components may further include a third harmonic magnetic field component that is an error component corresponding to a third harmonic of the ideal magnetic field component. The magnetic field component of the third harmonic causes an error that varies with ½ the predetermined period in the detection angle value. The angle sensor can correct the error caused by the third harmonic magnetic field component in the detection angle value.

The angle detection unit may perform correction processing to correct the error caused by the third harmonic magnetic field component in the detection angle value. The correction processing may include performing a conversion calculation to convert the first and second detection signals into first and second calculation signals to be used for the angle calculation for calculating the detection angle value. The conversion calculation may convert the first and second detection signals into the first and second calculation signals to allow the detection angle value to include a reduced error that varies with ½ the predetermined period as compared with the case of calculating the detection angle value using the first and second calculation signals second detection signals in the angle calculation.

One of the at least one first magnetic detection element and the at least one second magnetic detection element may include a magnetic layer provided with a third magnetic anisotropy. The magnetic layer provided with the third magnetic anisotropy is a layer whose direction of magnetization varies according to the direction of the rotating magnetic field at the detection position. The error caused by the magnetic field component of the third harmonic in the detection angle value may be corrected by the first or second magnetic anisotropy in the other of the at least one first magnetic detection element and the at least one second magnetic detection element and the third magnetic anisotropy. The third magnetic anisotropy may be magnetic shape anisotropy.

In the one of the at least one first magnetic detection element and the at least one second magnetic detection element, the magnetic layer provided with the third magnetic anisotropy may be other than the first or second magnetic layer. Alternatively, in the one of the at least one first magnetic detection element and the at least one second magnetic detection element, the first or second magnetic layer may be provided with the third magnetic anisotropy in addition to the first or second magnetic anisotropy.

The third magnetic anisotropy and the first or second magnetic anisotropy used to correct the error caused by the third harmonic field magnetic field component in the detection angle value may justify the same simple axis direction.

In the angle sensor system of the present invention, the at least one first magnetic detection element and the at least one second magnetic detection element may each include one or more magnetoresistive elements.

In the angle sensor system of the present invention, the magnetic field generating unit may be a magnet which is rotatable about a center axis. In such a case, the detection position may be outside the center axis. The angle to be detected may correspond to the rotational position of the magnet.

In the angle sensor system of the present invention, the magnetic field generating unit may be a magnet including a plurality of pairs of N and S poles arranged alternately in the first direction. In this case, the relative position of the magnet with respect to the detection position in the first direction may be variable. The angle to be detected may be an angle representing the relative position of the magnet with respect to the detection position, wherein a pitch of the magnet is 360 °.

The angle sensor system of the present invention utilizes the first and second magnetic anisotropies to reduce the angle error. which occurs due to the magnetic field component of the fifth harmonic. The present invention thus makes it possible to reduce the angular error associated with the rotating magnetic field generated by the magnetic field generating unit without complicating the configuration.

Other and further objects, features and advantages of the present invention will become more apparent from the following description.

list of figures

• 1 is a side view illustrating the general configuration of an angle sensor system according to a first embodiment of the invention.
• 2 FIG. 11 is a plan view illustrating the general configuration of the angle sensor system according to the first embodiment of the invention. FIG.
• 3 Fig. 12 is an explanatory diagram illustrating the definitions of directions and angles used in the first embodiment of the invention.
• 4 Fig. 10 is a circuit diagram illustrating a first example of a configuration of a detection unit of the first embodiment of the invention.
• 5 Fig. 10 is a circuit diagram illustrating a second example of an embodiment of the detection unit of the first embodiment of the invention.
• 6 FIG. 15 is a perspective view of a part of a magnetic detection element incorporated in FIG 4 is shown.
• 7 Fig. 10 is a functional block diagram illustrating the configuration of an angle detection unit of the first embodiment of the invention.
• 8th FIG. 15 is a waveform diagram illustrating an example of waveforms of first and second magnetic field components in the first embodiment of the invention. FIG.
• 9 FIG. 11 is a waveform diagram illustrating the waveform of an angle error resulting from the first and second magnetic field components included in FIG 8th are shown.
• 10 FIG. 15 is a waveform diagram illustrating waveforms of respective third harmonic magnetic field components of the first and second magnetic field components included in FIG 8th are shown.
• 11 FIG. 12 is a waveform diagram illustrating the waveform of an angle error resulting only from third harmonic magnetic field components that are in 10 are shown.
• 12 FIG. 15 is a waveform diagram illustrating waveforms of respective fifth-harmonic magnetic field components of the first and second magnetic field components shown in FIG 8th are shown.
• 13 FIG. 12 is a waveform diagram illustrating the waveform of an angle error resulting only from the fifth harmonic magnetic field components that are shown in FIG 12 are shown.
• 14 FIG. 12 is a waveform diagram illustrating an example of waveforms of first and second detection signals obtained when the first and second magnetic field components each consist of only one ideal magnetic field component in the first embodiment of the invention.
• 15 FIG. 15 is a waveform diagram illustrating the waveform of an angle error resulting only from respective third harmonic signal components of the first and second detection signals shown in FIG 14 are shown.
• 16 FIG. 12 is a waveform diagram illustrating an example of the waveform of an angle error occurring in a detection angle value obtained by performing angle calculation by the first and second detection signals in the first embodiment of the invention. FIG.
• 17 FIG. 12 is a waveform diagram illustrating an exemplary waveform of an angle error occurring in a detection angle value obtained by performing an angle calculation using the first and second calculation signals in the first embodiment of the invention. FIG.
• 18 Fig. 10 is a circuit diagram illustrating a first example of a configuration of a detection unit of a second embodiment of the invention.
• 19 Fig. 13 is a functional block diagram illustrating the configuration of an angle detection unit of the second embodiment of the invention.
• 20 FIG. 12 is a waveform diagram illustrating the waveform of an angle error resulting from first or second magnetic anisotropy and third magnetic anisotropy in the second embodiment of the invention.
• 21 is a circuit diagram illustrating the configuration of a detection unit of a Angle sensor represents a third embodiment of the invention.
• 22 FIG. 11 is an explanatory diagram illustrating a first state of an angle sensor system according to a fourth embodiment of the invention. FIG.
• 23 FIG. 10 is an explanatory diagram illustrating a second state of the angle sensor system according to the fourth embodiment of the invention. FIG.
• 24 FIG. 10 is an explanatory diagram illustrating a third state of the angle sensor system according to the fourth embodiment of the invention. FIG.
• 25 FIG. 10 is an explanatory diagram illustrating a fourth state of the angle sensor system according to the fourth embodiment of the invention. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

Preferred embodiments of the present invention will now be explained in detail with reference to the drawings. First, it will open 1 and 2 Reference is made to describe the general configuration of an angle sensor system according to a first embodiment of the invention. 1 FIG. 11 is a side view illustrating the general configuration of the angle sensor system according to the first embodiment. FIG. 2 FIG. 10 is a plan view illustrating the general configuration of the angle sensor system according to the first embodiment. FIG. The angle sensor system 1 According to the first embodiment, a magnetic field generating unit and an angle sensor 2.

The magnetic field generating unit of the present embodiment is a magnet 5 with a ring shape, on a rotating shaft 6 is stored, which is an object whose rotational position is to be detected. In response to the rotation of the rotary shaft 6 the magnet turns 5 around a center axis C in a rotational direction D. The angle to be detected in the present embodiment corresponds to the rotational position of the rotary shaft 6 and the rotational position of the magnet 5 , Hereinafter, the angle to be detected is referred to as "target angle" and represented by the reference character θ.

The magnet 5 , which serves as the magnetic field generating unit, has a magnetization in the direction indicated by the arrows 5 M in 2 is pictured. With this magnetization the magnet generates 5 a rotating magnetic field MF whose direction varies at a predetermined detection position PR according to the target angle θ. Hereinafter, the angle formed by the direction DM of the rotary magnetic field MF at the detection position PR against a predetermined reference direction DR will be referred to as a "rotating field angle" and represented by the symbol θM.

The angle sensor 2 is in particular a magnetic angle sensor. The angle sensor 2 detects the rotating magnetic field MF at the detection position PR and generates a detection angle value θs with a correspondence to the target angle θ.

The detection position PR is in a reference plane P, which is an imaginary plane parallel to an end face of the magnet 5 is and perpendicular to the center axis C. In the reference plane P, the direction DM of the rotating magnetic field MF rotates around the detection position PR. The reference direction DR is located in the reference plane P and intersects the detection position PR. In the following description, the direction DM of the rotating magnetic field MF at the detection position PR refers to a direction in the reference plane P.

The angle sensor 2 comprises a detection unit 10 and an angle detection unit 20. The angle detection unit 20 is in 1 or 2 not shown, but in 4 shown, which will be described later. The detection unit 10 touches or cuts the reference plane P. The relative position of the magnet 5 with respect to the detection unit 10 varies in the direction of rotation D about the center axis C.

Now, the definitions of directions and angles used in the present embodiment will be described with reference to FIGS 1 to 3 described. First, the Z direction is the direction parallel to the in 1 shown center axis C and runs in 1 up. In the 2 and 3 the Z-direction is out of the plane of the drawing. Next, the X and Y directions are two directions perpendicular to the Z direction and orthogonal to each other. In 1 the x-direction is to the right and the y-direction is to the plane of the drawing. In the 2 and 3 the X-direction is to the right and the Y-direction is upwards. Further, the -X direction is the direction opposite to the X direction, and the -Y direction is the direction opposite to the Y direction.

The detection position PR is the position where the angle sensor 2 detects the rotary magnetic field MF. The reference direction DR is the X direction. The direction DM of the rotary magnetic field MF rotates in 3 counterclockwise. The target angle θ and the rotational field angle θM are expressed in positive values as viewed from the reference direction DR in the counterclockwise direction, and expressed in negative values from the reference direction DR in the clockwise direction.

A first direction D1 and a second direction D2 refer to two directions in the reference plane P which are orthogonal to each other. In the present embodiment, the first direction D1 is the X direction, and the second direction D2 is the Y direction.

As in 3 1, the rotary magnetic field MF at the detection position PR includes a first magnetic field component MF1 in the first direction D1 and a second magnetic field component MF2 in the second direction D2.

The embodiment of the detection unit 10 will now be described in detail with reference to 4 and 5 described. 4 Fig. 10 is a circuit diagram showing a first example of an embodiment of the detection unit 10 represents. 5 Fig. 10 is a circuit diagram showing a second example of an embodiment of the detection unit 10 represents. The registration unit 10 comprises a first detection signal generating unit 11 and a second detection signal generation unit 12 ,

The first detection signal generation unit 11 generates a first detection signal S1 corresponding to the cosine of the angle which the direction DM of the rotating magnetic field MF forms at the detection position PR with respect to the first direction D1. The second detection signal generation unit 12 generates a second detection signal S2 corresponding to the sine of the angle formed by the direction DM of the rotating magnetic field MF at the detection position PR with respect to the first direction D1. In the present embodiment, the first direction D1 is the same direction as the reference direction DR. Therefore, the angle formed by the direction DM of the rotary magnetic field MF at the detection position PR with respect to the first direction D1 is equal to the rotary field angle θM.

The first detection signal generation unit 11 comprises at least a first magnetic detection element for detecting the rotary magnetic field MF. The at least one first magnetic detection element comprises a first magnetic layer whose magnetization direction varies according to the direction DM of the rotary magnetic field MF at the detection position PR. The first magnetic layer is provided with a first magnetic anisotropy.

The second detection signal generation unit 12 comprises at least a second magnetic detection element for detecting the rotary magnetic field MF. The at least one second magnetic detection element comprises a second magnetic layer whose magnetization direction varies according to the direction DM of the rotary magnetic field MF at the detection position PR. The second magnetic layer is provided with a second magnetic anisotropy.

Both the first and the second magnetic anisotropy are e.g. magnetic shape anisotropies. The simple axis direction established by the first magnetic anisotropy and the simple axis direction established by the second magnetic anisotropy are orthogonal to each other.

The at least one first magnetic detection element and the at least one second magnetic detection element may each comprise one or more magnetoresistive elements. The one or more magnetoresistive elements may be giant magnetoresistive element (s) (GMR element (s)), magnetic tunnel resistance element (s) (TMR element (s)) or anisotropic magnetoresistive element (s) (AMR element (s)) be.

When the target angle θ varies with a predetermined period so as to cause the direction DM of the rotary magnetic field MF to vary with the predetermined period, each of the first and second detection signals S1 and S2 periodically varies with a signal period equal to the aforementioned predetermined period is. The phase of the second detection signal S2 preferably differs from that of the first detection signal S1 by 90 °. In view of manufacturing tolerances of the magnetic detection element and other factors, the phase difference between the first detection signal S1 and the second detection signal S2 may slightly deviate from 90 °. In the following description, the first detection signal S1 and the second detection signal S2 have a phase difference of 90 °.

It will now be referred to 4 and 5 to an example of the specific configuration of the first and second detection signal generating units 11 and 12 to describe. In this example, the first detection signal generation unit 11 includes a Wheatstone bridge circuit 14 and a difference detector 15. The second detection signal generation unit 12 includes a Wheatstone bridge circuit 16 and a difference detector 17 ,

Each of the Wheatstone bridge circuits 14 and 16 includes four magnetic detection elements R1, R2, R3 and R4, a power supply terminal V, a ground terminal G, a first output terminal E1, and a second output terminal E2. The magnetic detection element R1 is provided between the power supply terminal V and the first output terminal E1. The magnetic detection element R2 is provided between the first output terminal E1 and the ground terminal G. The magnetic detection element R3 is provided between the power supply terminal V and the second output terminal E2. The magnetic detection element R4 is provided between the second output terminal E2 and the ground terminal G. A supply voltage of a predetermined size is applied to the power supply terminal V. The earth connection G is earthed.

Each of the magnetic detection elements R1, R2, R3, and R4 may comprise a plurality of series-connected magnetoresistive elements (MR elements). Each of the plurality of MR elements is, for example, a spin valve MR element. The spin valve MR element comprises a magnetization-fixed layer whose magnetization direction is fixed, a free layer which is a magnetic layer whose magnetization direction varies according to the direction DM of the rotary magnetic field MF at the detection position PR, and a non-magnetic layer is located between the layer with fixed magnetization and the free layer. The spin valve MR element may be a TMR element or a GMR element. In the TMR element, the nonmagnetic layer is a tunnel barrier layer. In the GMR element, the non-magnetic layer is a nonmagnetic conductive layer. The spin valve MR element varies in resistance according to the angle formed by the magnetization direction of the free layer to the magnetization direction of the magnetization-fixed layer, and has a minimum resistance when the aforementioned angle is 0 °, and a maximum resistance when the aforementioned Angle is 180 °. In 4 and 5 The filled arrows indicate the magnetization directions of the magnetization-fixed layers of the MR elements.

At the first detection signal generation unit 11 For example, the magnetization-defining layers of the MR elements included in the magnetic detection elements R1 and R4 are magnetized in the first direction D1 (the X direction), and the magnetization-defining layers of the MR elements included in the magneto-sensing elements R2 and R3 are magnetized in the direction opposite to the first direction D1. In this case, the potential difference between the output terminals E1 and E2 of the Wheatstone bridge circuit varies 14 according to the cosine of the rotating field angle θM. The difference detector 15 outputs a signal corresponding to the potential difference between the output terminals E1 and E2 of the Wheatstone bridge circuit 14 as the first detection signal S1. The first detection signal generating unit 11 thus generates the first detection signal S1 corresponding to the cosine of the rotating field angle θM.

In the second detection signal generation unit 12 For example, the magnetization-fixed layers of the MR elements included in the magnetic detection elements R1 and R4 are magnetized in the second direction (the Y direction), and the magnetization-fixed layers of the MR elements included in the magnetic detection elements R2 and R3 are magnetized in the opposite direction to the second direction D2 direction. In this case, the potential difference between the output terminals E1 and E2 of the Wheatstone bridge circuit varies 16 according to the sine of the rotating field angle θM. The difference detector 17 outputs a signal corresponding to the potential difference between the output terminals E1 and E2 of the Wheatstone bridge circuit 16 as the second detection signal S2. The second detection signal generating unit 12 therefore generates the second detection signal S2 corresponding to the sine of the rotating field angle θM.

In view of the manufacturing tolerances of the MR elements and other factors, the magnetization directions of the magnetization-fixed layers of the plurality of MR elements in the detection signal generation units can be made 11 and 12 slightly different from the above directions.

Each of the magnetic detection elements R1, R2, R3 and R4 in the first detection signal generation unit 11 includes at least one MR element including a free layer provided with a first magnetic anisotropy. The free layer provided with the first magnetic anisotropy corresponds to the first magnetic layer. In the present embodiment, in particular, the free layers of all of the MR elements included in the first detection signal generation unit 11 are included, provided with the first magnetic anisotropy.

Each of the magnetic detection elements R1, R2, R3 and R4 in the second detection signal generation unit 12 includes at least one MR element including a free layer provided with the second magnetic anisotropy. The free layer provided with the second magnetic anisotropy corresponds to the second magnetic layer. In particular, in the present embodiment, the free layers of all MR elements included in the second detection signal generation unit 12 are included, provided with the second magnetic anisotropy.

Now, a description will be given of the differences between the detection unit 10 of the first example, shown in 4 , and the detection unit 10 of the second example, shown in FIG 5 , In 4 and 5 That is, the major axis direction of the ellipses representing the magnetic detection elements R1, R2, R3, and R4 in the first detection signal generation unit 11 corresponds to the simple axis direction established by the first magnetic anisotropy. The major axis direction of the ellipses representing the magnetic detection elements R1, R2, R3, and R4 in the second detection signal generation unit 12 corresponds to the simple axis direction established by the second magnetic anisotropy.

In the first detection signal generation unit 11 the registration unit 10 represented in 4 , the simple axial direction established by the first magnetic anisotropy is parallel to the X direction. In this example, the simple axis direction established by the first magnetic anisotropy is parallel to the magnetization directions of the magnetization-fixed layers of the MR elements included in the magnetic detection elements R1, R2, R3 and R4 of the first detection signal generation unit 11. In the second detection signal generation unit 12 of the detection unit 10 , in the 4 is shown, the simple axis direction established by the second magnetic anisotropy is parallel to the Y direction. In this example, the simple axis direction established by the second magnetic anisotropy is parallel to the magnetization directions of the magnetization-defining layers of the MR elements included in the magnetic detection elements R1, R2, R3 and R4 of the second detection signal generation unit 12.

In the first detection signal generation unit 11 the registration unit 10 represented in 5 , the simple axis direction established by the first magnetic anisotropy is parallel to the Y direction. In this example, the simple axis direction established by the first magnetic anisotropy is orthogonal to the magnetization directions of the magnetization-fixed layers of the MR elements included in the magnetic detection elements R1, R2, R3, and R4 of the first detection signal generation unit 11. In the second detection signal generation unit 12 of the detection unit 10 represented in 5 , the simple axis direction established by the second magnetic anisotropy is parallel to the X direction. In this example, the simple axis direction established by the second magnetic anisotropy is orthogonal to the magnetization directions of the magnetization-fixed layers of the MR elements included in the magnetic detection elements R1, R2, R3 and R4 of the second detection signal generation unit 12.

In the present embodiment, as mentioned above, both the first and the second magnetic anisotropy are e.g. magnetic shape anisotropies. In this case, shaping the MR elements into a shape that is long in one direction, for example, an elliptical shape, viewed in a direction perpendicular to the interface between the free layer and the nonmagnetic layer, enables the first and second magnetic fields to be adjusted Anisotropies such that the longitudinal direction of the MR elements coincides with a simple axis direction.

In view of the manufacturing tolerances of the MR elements and other factors, the simple axis directions established by the first and second magnetic anisotropies may be slightly different from the above directions.

In the present embodiment, one of the first and second examples shown in FIG 4 and 5 , are selected, and the amounts of the first and second magnetic anisotropies are determined according to the error components included in each of the first and second magnetic field components MF1 and MF2. This will be explained later in detail.

An exemplary embodiment of the magnetic detection elements will now be described with reference to FIG 6 described. 6 FIG. 15 is a perspective view illustrating a part of a magnetic detection element in the angle sensor. FIG 2 who in 4 or 5 is shown, shows. In this example, the magnetic detection element includes a plurality of lower electrodes 162 , a variety of MR elements 150 and a plurality of upper electrodes 163 , The variety of lower electrodes 162 is disposed on a substrate (not shown). Each of the lower electrodes 162 has a long, narrow shape. Two each of the lower electrodes 162 in the longitudinal direction of the lower electrodes 162 lie next to each other, have a gap between them. As in 6 The MR elements 150 are shown on the upper sides of the lower electrodes 162 provided near opposite ends in the longitudinal direction. Each of the MR elements 150 comprises a free layer 151, a non-magnetic layer 152 , a layer with fixed magnetization 153 , and an antiferromagnetic layer 154 which are stacked in this order, with the free layer 151 the lower electrode 162 is closest. The free layer 151 is with the lower electrode 162 electrically connected. The antiferromagnetic layer 154 is from an antiferromagnetic Material formed. The antiferromagnetic layer 154 is in exchange coupling with the layer with fixed magnetization 153 to the magnetization direction of the magnetization-fixed layer 153 set. The variety of upper electrodes 163 is about the multitude of MR elements 150 arranged. Each of the upper electrodes 163 has a long, narrow shape and creates an electrical connection between the respective antiferromagnetic layers 154 of second adjacent MR elements 150 on two lower electrodes 162 arranged in the longitudinal direction of the lower electrodes 162 lie next to each other. With this configuration, the plurality of MR elements 150 in the magnetic detection element incorporated in 6 is shown about the plurality of lower electrodes 162 and the plurality of upper electrodes 163 connected in series. It is noted that the layers 151 to 154 the MR elements 150 in the reverse order to that in 6 shown can be stacked.

At the in 6 example shown, the free layer 151 to provide the above-mentioned magnetic shape anisotropy is every MR element 150 , in the direction perpendicular to the interface between the free layer 151 and the non-magnetic layer 152 considered shaped so that it is elliptical.

It will be up now 7 Referenced to the angle detection unit 20 to describe. The angle detection unit 20 generates the detection angle value θs on the basis of the first and second detection signals S1 and S2. The angle detection unit 20 includes analog / digital converter (hereinafter "A / D converter") 21 and 22, a correction processing unit 23, and an angle calculation unit 24 ,

The A / D converter 21 converts the first detection signal S1 into a digital signal. The A / D converter 22 converts the second detection signal S2 into a digital signal. The correction processing unit 23 performs correction processing on the digital signals converted by the A / D converters 21 and 22 from the first and second detection signals S1 and S2 to thereby generate a first calculation signal Sa and a second calculation signal Sb. Hereinafter, for clarity, the digital signals converted from the first and second detection signals S1 and S2 for use in the correction processing will be simply referred to as the first and second detection signals S1 and S2.

The angle calculation unit 24 performs an angle calculation using the first and second calculation signals Sa and Sb to calculate the detection angle value θs. The correction processing unit 23 and the angle calculation unit 24 may be implemented by, for example, an application specific integrated circuit (ASIC) () or a microcomputer.

Now, a description will be given of the correction processing to be performed by the correction processing unit 23. The correction processing includes a conversion calculation to convert the first and second detection signals S1 and S2 into the first and second calculation signals Sa and Sb for use in the angle calculation to calculate the detection angle value θs.

$$\text{S2a}=\left(\text{S2}-{\text{S2}}_{\text{off}}\right)/{\text{S2}}_{\text{amp}}\cdot \text{CP}1$$

In the conversion calculation, first, the signals S1a and S2a corresponding to the signals S1 and S2 are generated by performing calculations using functions for correcting for offsets and amplitudes. Specifically, in the correction processing, the signals S1a and S2a are generated by the functions expressed in the following equations (1) and (2), respectively: $$\text{S}1\text{a}=\left(\text{S}1-\text{<figure-callout id="1" label="S" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">S</figure-callout>}{1}_{\text{off}}\right)/\text{<figure-callout id="1" label="S" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">S</figure-callout>}{1}_{\text{amp}}/\text{<figure-callout id="1" label="CP" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">CP</figure-callout>}1$$

$$\text{S2a}=\left(\text{S2}-{\text{S2}}_{\text{off}}\right)/{\text{S2}}_{\text{amp}}\cdot \text{<figure-callout id="1" label="CP" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">CP</figure-callout>}1$$

In equation (1), S1 and S1 _{amp off} the offset and the amplitude of the first signal S1. In equation (2) S2 and S2 _off filters _amp offset and the amplitude of the signal S2. The offset S1 _off and the amplitude S1 _amp are determined from the waveform for at least one period of the signal S1. The offset S2 _off and the amplitude S2 _amp are determined from the waveform for at least one period of the signal S2. The waveforms for at least one period of the signals S1 and S2 may be prior to shipment or use of the angle sensor system 1 be generated.

Each of equations (1) and (2) includes a correction parameter CP1. The correction parameter CP1 has a value of 1 or near 1. When the correction parameter CP1 is 1, equations (1) and (2) represent fundamental calculations for correcting the offsets and amplitudes of the signals S1 and S2 1, the signals S1a and S2a are given the same amplitude. When the correction parameter CP1 is not equal to 1, the signals S1a and S2a are not given the same amplitude.

$$\text{Sbp}=\text{S}1\text{a+S}2\text{a}$$

In the conversion calculation, then, using the functions expressed in equations (3) and (4), respectively, a first initial one is obtained Calculation signal Sap and a second initial calculation signal Sbp generated. $$\text{Sap}=\text{S}1\text{a}-\text{S}2\text{a}$$

$$\text{sbp}=\text{S}1\text{a + S}2\text{a}$$

$$\text{Sb}={\text{Sbp/Sbp}}_{\text{amp}}\cdot \text{CP}2$$

In the conversion computation, using the equations (5) and 6 ) generates the first calculation signal Sa and the second calculation signal Sb. $$\text{Sat.}={\text{Sap / Sap}}_{\text{amp}}/\text{<figure-callout id="2" label="CP" filenames="DE102018103442A1\_0015.png,DE102018103442A1\_0016.png" state="{{state}}">CP</figure-callout>}2$$

$$\text{sb}={\text{Sbp / sbp}}_{\text{amp}}\cdot \text{<figure-callout id="2" label="CP" filenames="DE102018103442A1\_0015.png,DE102018103442A1\_0016.png" state="{{state}}">CP</figure-callout>}2$$

In Equation (5), Sap _{amp represents} the amplitude of the first initial calculation signal Sap. In Equation 6, Sbp _{amp represents} the amplitude of the second initial calculation signal Sbp. The amplitudes Sap _amp and Sbp _amp are determined from the waveforms for at least one period of the first and second second initial calculation signals Sap or Sbp determined. The waveforms for at least one period of the first and second initial calculation signals Sap and Sbp may be generated before shipping and using the angle sensor system 1.

Each of equations (5) and (6) includes a correction parameter CP2. The correction parameter CP2 has a value of 1 or close to 1.

When both the correction parameters CP1 and CP2 are 1, the equations (1) to (6) represent fundamental calculations for making the phase difference between the first and second calculation signals Sa and Sb 90 °, and the amplitudes of the first and second calculation signals Sa and Sb to be the same. When the correction parameter CP1 is other than 1, the phase difference between the first and second calculation signals Sa and Sb becomes close to 90 °, though not exactly 90 °. When the correction parameter CP2 is other than 1, the first and second calculation signals Sa and Sb do not receive the same amplitude. A method of determining the correction parameters CP1 and CP2 will be described later in detail.

Now, the angle calculation to be performed by the angle calculation unit 24 will be described. In the angle calculation, the detection angle value θs is calculated by using the first and second calculation signals Sa and Sb from the following equation (7). In equation (7), "atan" represents the arctangent function. $$\mathrm{\theta }\text{s}=\text{atan}\left(\text{Sb / Sa}\right)-\mathrm{\alpha }$$

In Equation (7), α represents the phase difference between the detection angle value θs and the angle determined by the calculation of atan (Sb / Sa).

If θs is within the range of 0 ° to less than 360 °, equation (7) results in two solutions that differ in value by 180 ° from each other. Which of the two solutions for θs in equation (7) is the true value of θs can be deduced from the combination of positive and negative signs of Sa and Sb. The angle calculation unit 24 determines θs within the range of 0 ° to less than 360 ° by using Equation (7) and the aforementioned determination from the combination of positive and negative signs of Sa and Sb.

Now the function and effects of the angle sensor system become 1 described according to the present invention. In the present embodiment, angle errors occurring in the detection angle value θs include an error associated with the rotating magnetic field MF and an error related to the angle sensor 2 , In the present embodiment, the angular error associated with the angle sensor 2 mainly results from the first and second magnetic anisotropies. It is noted that the angle error corresponds to the detection angle value θs minus the target angle θ.

First, a description will be given of the angle error associated with only the rotary magnetic field MF. When the target angle θ varies with a predetermined period, each of the first and second magnetic field components MF1 and MF2 of the rotary magnetic field MF includes an ideal magnetic field component, a third harmonic magnetic field component, and a fifth harmonic magnetic field component. The ideal magnetic field component varies periodically such that it maps an ideal sinusoidal curve. The third harmonic magnetic field component is an error component corresponding to the third harmonic of the ideal magnetic field component. The fifth harmonic magnetic field component is an error component corresponding to the fifth harmonic of the ideal magnetic field component. The ideal magnetic field component, the third harmonic magnetic field component and the fifth harmonic magnetic field component of the first magnetic field component MF1 are hereinafter referred to as MF10, MF1a and MF1b, respectively. The ideal magnetic field component, the third harmonic magnetic field component, and the fifth harmonic magnetic field component of the second Magnetic field component MF2 are represented by MF20, MF2a and MF2b, respectively.

The third harmonic magnetic field components MF1a and MF2a of the first and second magnetic field components MF1 and MF2 cause an angle error Ea in the detection angle value θs, and the angular error Ea varies with ½ the predetermined period. The fifth harmonic magnetic field components MF1b and MF2b of the first and second magnetic field components MF1 and MF2 cause an angle error Eb in the detection angle value θs, and the angular error Eb varies with ¼ of the predetermined period.

In the present embodiment, each of the first and second magnetic field components includes MF 1 and MF2 the magnetic field components of the third and fifth harmonics. As a result, the angle error Ea and the angle error Eb are combined in an angle error Eab in the detection angle value θs.

8th Fig. 12 illustrates an example of waveforms of the first and second magnetic field components MF1 and MF2. In 8th For example, the horizontal axis represents the target angle θ, and the vertical axis represents the first and second magnetic field components MF1 and MF2. The vertical axis is off 8th is in arbitrary units, where the maximum value of the ideal magnetic field components MF 10 and MF20 of the first and second magnetic field components MF1 and MF2 is 1. In 8th represents the curve MF 1 the waveform of the first magnetic field component MF 1 and the curve MF2 represents the waveform of the second magnetic field component MF2. The curve MF10 represents the waveform of the ideal magnetic field component of the first magnetic field component MF 1 and the curve MF20 represents the waveform of the ideal magnetic field component of the second magnetic field component MF2.

9 FIG. 12 illustrates the waveform of the angle error Eab resulting from the first and second magnetic field components MF1 and MF2, which are shown in FIG 8th are shown. In 9 the horizontal axis represents the target angle θ, and the vertical axis represents the angle error Eab.

10 FIG. 13 illustrates the waveforms of the third harmonic magnetic field components MF1a and MF2a of the first and second magnetic field components MF1 and MF2 shown in FIG 8th are shown. In 10 For example, the horizontal axis represents the target angle θ, and the vertical axis represents the third harmonic magnetic field components MF1a and MF2a. The vertical axis is off 10 is in arbitrary units, with the maximum value of the ideal magnetic field components MF10 and MF20 of the first and second magnetic field components MF1 and MF2 being 1. In 10 For example, the curve MF1a represents the waveform of the third harmonic magnetic field component MF1a, and the curve MF2a represents the third harmonic wave magnetic field component MF2a.

11 FIG. 12 illustrates the angle error Ea, which is composed only of the third harmonic magnetic field components MF1a and MF2a of the first and second magnetic field components MF1 and MF2 shown in FIG 10 , results. In 11 The horizontal axis represents the target angle θ, and the vertical axis represents the angle error Ea.

12 FIG. 14 illustrates the waveforms of the fifth harmonic magnetic field components MF1b and MF2b of the first and second magnetic field components MF1 and MF2 shown in FIG 8th are shown. In 12 For example, the horizontal axis represents the target angle θ, and the vertical axis represents the fifth harmonic magnetic field components MF1b and MF2b. The vertical axis is off 12 is in arbitrary units, with the maximum value of the ideal magnetic field components MF10 and MF20 of the first and second magnetic field components MF1 and MF2 being 1. In 12 The curve MF1b represents the waveform of the fifth harmonic magnetic field component MF1b, and the curve MF2b represents the fifth harmonic magnetic field component MF2b waveform.

13 FIG. 12 illustrates the waveform of the angular error Eb formed only of the fifth harmonic magnetic field components MF1b and MF2b of the first and second magnetic field components MF 1 and MF2 results in 12 are shown. In 13 The horizontal axis represents the target angle θ, and the vertical axis represents the angle error Eb.

The waveform of the ideal magnetic field component MF10 of the first magnetic field component MF1 shown in FIG 8th can be represented by cosθ, and the waveform of the ideal magnetic field component MF20 of the second magnetic field component MF2 shown in FIG 8th can be represented by sinθ.

The waveform of the third harmonic magnetic field component MF1a of the first magnetic field component MF1 shown in FIG 10 can be represented by A ₁ • cos 3θ, and the waveform of the third harmonic magnetic field component MF 2 a of the second magnetic field component MF 2 shown in FIG 10 can be represented by A ₁ • sin 3θ. Where A ₁ is a real number. In the in 10 As shown, A _{1 is} a positive value.

The waveform of the fifth harmonic magnetic field component MF1b of the first magnetic field component MF1 shown in FIG 12 can be represented by B ₁ • cos5θ, and the waveform of the fifth harmonic magnetic field component MF2b of the second magnetic field component MF2 shown in FIG 12 can be represented by B ₁ • sin5θ. Here, B _{1 is} a real number. In the in 12 As shown, B _{1 is} a positive value.

$$\text{S2}=\text{sin}\mathrm{\theta }+{\text{A}}_1\cdot \text{sin}3\mathrm{\theta }+{\text{B}}_1\cdot \text{sin}5\mathrm{\theta }$$

Assuming that the angle error Eab is the only angle error occurring in the detection angle value θs, the first and second detection signals S1 and S2 can be represented by the following equations (8) and (9), respectively. $$\text{<figure-callout id="1" label="S" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">S</figure-callout>}1=\text{cos}\mathrm{\theta }+{\text{A}}_1\cdot \text{<figure-callout id="3" label="cos" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">cos</figure-callout>}3\mathrm{\theta }+{\text{<figure-callout id="1" label="B" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">B</figure-callout>}}_1\cdot \text{<figure-callout id="5" label="cos" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">cos</figure-callout>}5\mathrm{\theta }$$

$$\text{S2}=\text{sin}\mathrm{\theta }+{\text{A}}_1\cdot \text{<figure-callout id="3" label="sin" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">sin</figure-callout>}3\mathrm{\theta }+{\text{<figure-callout id="1" label="B" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">B</figure-callout>}}_1\cdot \text{<figure-callout id="5" label="sin" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">sin</figure-callout>}5\mathrm{\theta }$$

Next, a description will be given of an angle error occurring in the detection angle value θs due to the first and second magnetic anisotropies. First, let it be assumed that the first and second magnetic field components MF1 and MF2 are composed only of the ideal magnetic field components MF 10 and MF20, respectively, when the target angle θ varies with a predetermined period. In such a case, each of the first and second detection signals S1 and S2 includes an ideal signal component and a third harmonic signal component. The ideal signal component varies periodically such that it maps an ideal sinusoidal curve. The signal component of the third harmonic is an error component corresponding to the third harmonic of the ideal signal component. The ideal signal components of the first and second detection signals S1 and S2 are represented by S10 and S20, respectively. The third harmonic signal components of the first and second detection signals S1 and S2 result from the first and second magnetic anisotropies, respectively. The third harmonic signal components of the first and second detection signals S1 and S2 cause an angle error Ec in the detection angle value θs, and the angle error Ec varies with ¼ of the predetermined period.

14 FIG. 12 illustrates an example of waveforms of the first and second detection signals S1 and S2 obtained based on the assumption that the first and second magnetic field components MF 1 and MF2 only from the ideal magnetic field components MF 10 or MF20. In 14 the horizontal axis represents the target angle θ, and the vertical axis represents the first and second detection signals S1 and S2 14 the curve S1 represents the waveform of the first detection signal S1, and the curve S2 represents the waveform of the second detection signal S2. The curve S10 represents the waveform of the ideal signal component S10 of the first detection signal S1, and the curve S20 represents the waveform of the ideal signal component S20 of the second detection signal S2.

15 FIG. 12 illustrates the waveform of the angle error Ec resulting only from the third harmonic signal components of the first and second detection signals S1 and S2, which are shown in FIG 14 are shown. In 15 For example, the horizontal axis represents the target angle θ, and the vertical axis represents the angle error Ec.

The waveform of the ideal signal component S10 of the first detection signal S1 shown in FIG 14 , can be represented by cosθ, and the waveform of the ideal signal component S20 of the second detection signal S20 shown in FIG 14 , can be represented by sinθ. The signal component of the third harmonic of the first detection signal S1, which in 14 can be represented by C ₁ • cos 3θ, and the third harmonic signal component of the second detection signal S 2 shown in FIG 14 , can be represented by -C ₁ • sin 3θ. Here, C _{1 is} a real number. In the in 14 As shown, C _{1 is} a positive value.

$$\text{S2}=\text{sin}\mathrm{\theta -}{\text{C}}_1\cdot \text{sin}3\mathrm{\theta }$$

Assuming that the angular error Ec is the only angular error occurring in the detection angle value θs, the first and second detection signals S1 and S2 can be represented by the following equations (10) and (11), respectively. $$\text{<figure-callout id="1" label="S" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">S</figure-callout>}1=\text{cos}\mathrm{\theta }+{\text{<figure-callout id="1" label="C" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">C</figure-callout>}}_1\cdot \text{<figure-callout id="3" label="cos" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">cos</figure-callout>}3\mathrm{\theta }$$

$$\text{S2}=\text{sin}\mathrm{\theta -}{\text{<figure-callout id="1" label="C" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">C</figure-callout>}}_1\cdot \text{<figure-callout id="3" label="sin" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">sin</figure-callout>}3\mathrm{\theta }$$

As in 13 2, the angle error Eb, which is composed only of the fifth harmonic magnetic field components MF1b and MF2b of the first and second magnetic field components MF, varies 1 and MF2 results with ¼ of the given period. As in 15 As shown, the angle error Ec resulting only from the signal components of the third harmonic of the first and second detection signals S1 and S2 also varies with ¼ of the predetermined period. If C ₁ and B _{1 have} the same positive or negative sign, the angular error Eb and the angular error Ec have a phase difference of 45 °. In particular, when C ₁ and B _{1 are} equal, the angular error Eb and the angular error Ec have a phase difference of 45 ° and have the same amplitude. If the angular error Eb and the angular error Ec have such a relationship, an angle error can be calculated with ¼ of the given Period varies in which the detection angle value θs are theoretically completely reduced to zero.

The positive or negative sign of C ₁ can be changed by changing the simple axis directions established by the first and second magnetic anisotropies. For example, the in 4 illustrated embodiment C ₁ to a negative value, and the in 5 illustrated embodiment makes C ₁ to a positive value. The amount of C ₁ can be changed by changing the magnitudes of the first and second magnetic anisotropies.

The present embodiment utilizes the above-described property for reducing the angular error Eb resulting from the fifth harmonic magnetic field components MF1 and MF2 by means of the first and second magnetic anisotropies as follows. Specifically, in the present embodiment, the first and second magnetic anisotropies are set so as to allow the detection angle value θs to contain a reduced angle error that varies with ¼ of the predetermined period compared to both the angle error Eb and the angle error Ec.

$$\text{S2}=\text{sin}\mathrm{\theta }+{\text{A}}_1\cdot \text{sin}3\mathrm{\theta +}{\mathrm{{\rm B}}}_1\cdot \text{sin}5\mathrm{\theta -}{\text{C}}_1\cdot \text{sin}3\mathrm{\theta }$$

According to the present embodiment, when all of the third and fifth harmonic magnetic field components MF1a, MF2a, MF1b, and MF2b of the first and second magnetic field components MF 1 and MF2 and the third harmonic signal components of the first and second detection signals S1 and S2 are considered, the first and second detection signals are represented by the following equations (12) and (13), respectively. $$\text{<figure-callout id="1" label="S" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">S</figure-callout>}1=\text{cos}\mathrm{\theta }+{\text{A}}_1\cdot \text{<figure-callout id="3" label="cos" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">cos</figure-callout>}3\mathrm{\theta \; +}{\mathrm{<figure-callout\; id="1"\; label="{\rm B}"\; filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png"\; state="\{\{state\}\}">{\rm B}</figure-callout>}}_1\cdot \text{<figure-callout id="5" label="cos" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">cos</figure-callout>}5\mathrm{\theta }+{\text{<figure-callout id="1" label="C" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">C</figure-callout>}}_1\cdot \text{<figure-callout id="3" label="cos" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">cos</figure-callout>}3\mathrm{\theta }$$

$$\text{S2}=\text{sin}\mathrm{\theta }+{\text{A}}_1\cdot \text{<figure-callout id="3" label="sin" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">sin</figure-callout>}3\mathrm{\theta \; +}{\mathrm{<figure-callout\; id="1"\; label="{\rm B}"\; filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png"\; state="\{\{state\}\}">{\rm B}</figure-callout>}}_1\cdot \text{<figure-callout id="5" label="sin" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">sin</figure-callout>}5\mathrm{\theta -}{\text{<figure-callout id="1" label="C" filenames="DE102018103442A1\_0016.png,DE102018103442A1\_0017.png" state="{{state}}">C</figure-callout>}}_1\cdot \text{<figure-callout id="3" label="sin" filenames="DE102018103442A1\_0019.png,DE102018103442A1\_0020.png" state="{{state}}">sin</figure-callout>}3\mathrm{\theta }$$

Here, consider a case where the detection angle value θs is calculated by performing an angle calculation defined by the following equation (14), using the first and second detection signals S1 and S2 represented by equations (12) and (13 ) given are. $$\mathrm{\theta }=\text{atan}\left(\text{<figure-callout id="2" label="S" filenames="DE102018103442A1\_0015.png,DE102018103442A1\_0016.png" state="{{state}}">S</figure-callout>}2/\text{S}1\right)$$

An angle error occurring in the detection angle value θs is represented by the reference Eabc in this case. 16 illustrates an exemplary waveform of the angle error Eabc. In 16 For example, the horizontal axis represents the target angle θ, and the vertical axis represents the angle error Eabc. In this case, C ₁ = B ₁ .

At the in 16 Angular error Eabc is the angular error component that varies with ¼ of the given period, smaller than both the in 13 shown angle error Eb as well as the in 15 Angle error Ec shown. This shows that the present embodiment, the reduction of the angular error Eb, which consists of the magnetic field components of the fifth harmonic MF 1b and MF2b of the first and second magnetic field components MF 1 and MF2 results by means of the first and second magnetic anisotropies.

Now, an exemplary method for determining C ₁ and the simple axis directions and sizes of the first and second magnetic anisotropies will be described. First, the waveform of the angle error Eb is determined by B ₁ . B ₁ is therefore obtainable from the waveform of the angular error Eb.

In order for the detection angle value θs to contain a reduced angle error that varies with ¼ of the predetermined period compared to both the angle error Eb and the angle error Ec, C ₁ is determined to have the same positive or negative sign as B ₁ and to be makes the amount of (B ₁ -C ₁ ) smaller than the amount of B ₁ . The smaller the amount of (B ₁ -C ₁ ), the more preferable it is. The amount of (B ₁ -C ₁ ) is preferably less than or equal to 1/2 of the amount of B ₁ .

As previously mentioned, the positive or negative sign of C _{1 can be made} by changing the simple axis direction established by the first and second magnetic anisotropies. The amount of C ₁ has a relation to the amounts of the first and second magnetic anisotropies. By obtaining, in advance, the relationships between C ₁ and the simple axis directions and the magnitudes of the first and second magnetic anisotropies, it is possible to determine the simple axis directions and magnitudes of the first and second magnetic anisotropies based on the obtained relationships to obtain a desired value of C ₁ .

When the first and second magnetic field components MF1 and MF2 include the third harmonic magnetic field components MF1a and MF2a respectively, calculating the detection angle value θs by performing angle calculation using the first and second detection signals S1 and S2 results in the occurrence of the angle error Eabc in the detection angle value θs. As in 16 shown, the angle error Eabc contains an angle error with ½ of the predetermined period varied. The angle error component that varies with ½ the predetermined period corresponds to the error caused by the third harmonic magnetic field components MF1a and MF2a in the detection angle value θs. This angular error component will be referred to as "second order magnetic field related angular error" hereinafter.

In the present embodiment, the in 7 represented correction processing by the correction processing unit 23 is performed, the second-order magnetic-field-related angle error. It is noted that the correction of the second-order magnetic-field angular error is the reduction of the angular error component, which varies with ½ the predetermined period, in the detection angle value θs.

Now, the relationships between the second order magnetic field angle error and the correction parameters CP1 and CP2 will be described. The magnetic-field-related angular error of the second order contains a first component and a second component. The first component and the second component have a phase difference of 45 °. The amplitude of the first component varies depending on the value of the correction parameter CP1. The first component can therefore be reduced by adjusting the value of the correction parameter CP1 according to the amplitude of the first component. The amplitude of the second component varies depending on the value of the correction parameter CP2. The second component can thus be reduced by adjusting the value of the correction parameter CP2 according to the amplitude of the second component. For example, the amplitudes of the first and second components may be obtained by subjecting the second order magnetic field related angular error to Fourier transformation.

Now, Es should represent the angular error of the detection angle value θs when passing through the angle calculation unit 24 is calculated by using the first and second calculation signals Sa and Sb received from the correction processing unit 23 be issued. 17 illustrates an exemplary waveform of the angle error Es. This example corresponds to a case where the correction processing with the correction parameter CP1 set to 0.92 and the correction parameter CP2 set to 1 has been performed. In 17 For example, the horizontal axis represents the target angle θ, and the vertical axis represents the angle error Es 17 shown is the angle error It is sufficiently smaller than the angle error Eab, shown in 9 , and also smaller than the angle error Eabc, shown in FIG 16 ,

Against this background, the present embodiment enables the reduction of the angular error associated with the rotating magnetic field MF generated by the magnetic field generating unit. In the present embodiment, the angle sensor requires 2 no plurality of pairs of signal generation units 11 and 12 but only a pair of detection signal generating units 11 and 12 , Therefore, the present embodiment makes it possible to reduce the angular error associated with the rotating magnetic field MF generated by the magnetic field generating unit without complexity in the configuration.

Second Embodiment

A second embodiment of the present invention will now be described. 18 FIG. 12 is a circuit diagram illustrating a first example of an embodiment of the detection unit of the second embodiment. FIG. 19 FIG. 12 is a functional block diagram illustrating the configuration of the angle detection unit of the second embodiment. FIG. In the angle sensor system 1 According to the second embodiment, the angle sensor 2 another embodiment than that in the first embodiment.

The registration unit 10 of the angle sensor 2 The present embodiment includes a first detection signal generation unit 111 and a second detection signal generation unit 112 instead of the first detection signal generation unit 11 and the second detection signal generation unit 12 the first embodiment.

The first detection signal generation unit 111 includes at least a first magnetic detection element. The at least one magnetic detection element comprises a first magnetic layer. The first magnetic layer is provided with a first magnetic anisotropy.

The second detection signal generation unit 112 includes at least a second magnetic detection element. The at least one second magnetic detection element comprises a second magnetic layer. The second magnetic layer is provided with a second magnetic anisotropy.

Both the first and the second magnetic anisotropy are magnetic shape anisotropies, for example. The simple axis direction established by the first magnetic anisotropy and the simple axis direction established by the second magnetic anisotropy are orthogonal to each other.

In the present embodiment, the at least one first magnetic detection element or the at least one second magnetic detection element comprises a magnetic layer which is provided with a third magnetic anisotropy. The magnetic layer provided with the third magnetic anisotropy is a layer whose direction of magnetization varies in accordance with the direction DM of the rotary magnetic field MF at the detection position PR. The third magnetic anisotropy is, for example, a magnetic shape anisotropy.

In the present embodiment, in the one of the at least one first magnetic detection element and the at least one second magnetic detection element, the magnetic layer provided with the third magnetic anisotropy is different from the first or second magnetic layer.

In the present embodiment, the error caused by the third harmonic magnetic field components MF1a and MF2a in the detection angle value θs, that is, the second order magnetic field related angle error described in connection with the first embodiment, is determined by using the first or second magnetic anisotropy in FIG other of the at least one first magnetic detection element and the at least one second magnetic detection element and the third magnetic anisotropy corrected. The third magnetic anisotropy and the first or second magnetic anisotropy used to correct the second-order magnetic field angle error justify the same simple axis direction.

It will be up now 18 Reference is made to a first example of the configuration of the first and second detection signal generating units 111 and 112 to describe in detail. In the first example, the first detection signal generation unit has 111 a Wheatstone bridge circuit 114 instead of the Wheatstone bridge circuit 14 the first embodiment. The second detection signal generation unit 112 has a Wheatstone bridge circuit 116 instead of the Wheatstone bridge circuit 16 the first embodiment.

Each of the Wheatstone bridge circuits 114 and 116 includes magnetic detection elements R11, R12, R21, R22, R31, R32, R41, and R42, a power supply terminal V, a ground terminal G, a first output terminal E1, and a second output terminal E2.

The magnetic detection elements R11 and R12 are connected in series and provided between the power supply terminal V and the first output terminal E1. The magnetic detection elements R21 and R22 are connected in series and provided between the first output terminal E1 and the ground terminal G. The magnetic detection elements R31 and R32 are connected in series and provided between the power supply terminal V and the second output terminal E2. The magnetic detection elements R41 and R42 are connected in series and provided between the second output terminal E2 and the ground terminal G. A supply voltage of a predetermined size is applied to the power supply terminal V. The ground connection G is grounded.

Each of the magnetic detection elements R11, R12, R21, R22, R31, R32, R41, and R42 includes one or more MR elements. Each MR element has the same configuration as in the first embodiment.

In the first detection signal generation unit 111 For example, the magnetization-fixed layers of the MR elements included in the magnetic detection elements R11, R12, R41, and R41 are magnetized in the first direction D1 (the X direction), and the magnetization-fixed layers of the MR elements, which are included in the magnetic detection elements R21, R22, R31 and R32 are magnetized in the opposite direction of the first direction D1.

In the second detection signal generation unit 112 For example, the magnetization-defining layers of the MR elements included in the magnetic detection elements R11, R12, R41 and R42 are magnetized in the second direction D2 (Y direction), and the magnetization-defining layers of the MR elements shown in FIG The magnetic detection elements R21, R22, R31, and R32 are magnetized in the opposite direction of the second direction D2.

In view of manufacturing tolerances of the MR elements and other factors, the magnetization directions of the magnetization-fixed layers of the MR elements in the detection signal generation units can be made 111 and 112 slightly different from the directions described above.

In the first example, the free layer of at least one of the one or more MR elements included in each of the magnetic detection elements R11, R12, R21, R22, R31, R32, R41, and R42 in the first detection signal generation unit 111 are included, provided with the first magnetic anisotropy. The free layer provided with the first magnetic anisotropy corresponds to the first magnetic layer.

The free layer of at least one of the one or more MR elements included in each of the magnetic detection elements R11, R21, R31, and R41 in the second detection signal generation unit 112 is provided with the second magnetic anisotropy. The free layer provided with the second magnetic anisotropy corresponds to the second magnetic layer.

The free layer of at least one of the one or more MR elements included in each of the magnetic detection elements R12, R22, R32, and R42 in the second detection signal generation unit 112 is provided with the third magnetic anisotropy.

In 18 The major axis direction of the ellipses representing the magnetic detection elements corresponds to the simple axis direction established by the magnetic anisotropy. In the first example, the simple axis direction established by the first magnetic anisotropy is parallel to the X direction, and the single axis direction established by the second magnetic anisotropy is parallel to the Y direction. Further, the simple axis direction established by the third magnetic anisotropy is parallel to the X direction, as in the simple axis direction established by the first magnetic anisotropy.

Now, the second to fourth examples of the configuration of the first and second detection signal generation units will be described 111 and 112 described. In the second example, the at least one first magnetic detection element in the first detection signal generation unit 111 includes a magnetic layer provided with the third magnetic anisotropy. In this case, for example, the free layer of at least one of the one or more MR elements included in each of the magnetic detection elements R12, R22, R32, and R42 in the first detection signal generation unit 111 are provided with the third magnetic anisotropy and the free layer of at least one of the one or more MR elements included in each of the magnetic detection elements R12, R22, R32, and R42 in the second detection signal generation unit 112 are included, is provided with the second magnetic anisotropy. The simple axis direction established by the third magnetic anisotropy is in this case parallel to the Y direction, as in the simple axis direction established by the second magnetic anisotropy.

In the third and fourth examples, as in the 5 As shown in the first embodiment, the simple axis direction established by the first magnetic anisotropy is parallel to the Y direction, and the single axis direction established by the second magnetic anisotropy is parallel to the X direction.

In the third example, the at least one second magnetic detection element includes in the second detection signal generation unit 112 a magnetic layer provided with the third magnetic anisotropy. In this case, the simple axis direction established by the third magnetic anisotropy is parallel to the Y direction, as in the simple axis direction established by the first magnetic anisotropy.

In the fourth example, the at least one magnetic detection element includes in the first detection signal generation unit 111 a magnetic layer provided with the third magnetic anisotropy. In this case, the simple axis direction established by the third magnetic anisotropy is parallel to the X direction, as in the simple axis direction established by the second magnetic anisotropy.

In consideration of the production accuracy of the MR elements and other factors, the simple axis directions in the above first to fourth examples may slightly deviate from the directions described above.

Now, the configuration of the angle detection unit 20 the present embodiment with reference to 19 described. The angle detection unit 20 of the present embodiment is set up by the correction processing unit 23 from the angle detection unit 20 the first embodiment is omitted. In the angle detection unit 20 In the present embodiment, the first and second detection signals S1 and S2 converted into digital signals by the A / D converters 21 and 22 are the angle calculation unit 24 entered. The angle calculation unit 24 calculates the detection angle value θs by performing the angle calculation defined in Equation (14) using the first and second detection signals S1 and S2.

Now, the operation and effects of the angle sensor system 1 described according to the present embodiment. First, assume that the first and second magnetic field components MF1 and MF2 consist only of the ideal magnetic field components MF 10 and MF20, respectively, when the target angle θ varies with a predetermined period. In such a case, the third magnetic anisotropy and the first or second magnetic anisotropy cause the second to correct the magnetic field angle error Order, an angle error which varies with ½ the predetermined period in the detection angle value θs. This angle error is hereinafter referred to as "element-related angle error second order" and provided with the reference symbol Ed.

20 FIG. 12 illustrates an example waveform of the second order elemental angular error Ed of the first in FIG 18 shown example. In 20 For example, the horizontal axis represents the target angle θ, and the vertical axis represents the second-order elemental angle error Ed.

When the simple axis direction established by the third magnetic anisotropy is parallel to the X direction, as in the third and fourth examples, the phase of the element-related angular error Ed has the in 20 shown waveform. On the other hand, when the simple axis direction established by the third magnetic anisotropy is parallel to the Y direction, as in the second and third examples, the element-related second-order angle error Ed is opposite to that in FIG 20 shown waveform a different phase by 90 °. The amplitude of the second-order elemental angular error Ed may be changed by changing the magnitudes of the third magnetic anisotropy and the first or second magnetic anisotropy used to correct the second-order magnetic field angular error.

In the present embodiment, the third magnetic anisotropy and the first or second magnetic anisotropy are adjusted to correct the second order magnetic field angle error to cause the second order magnetic field angle error and second order element angular error Ed to have a phase difference of 90 ° or nearly 90 ° °, and have the same or nearly the same amplitude. As a result, a correction of the magnetic-field-related angular error of the second order is achieved.

The present embodiment eliminates the need for the correction processing unit 23 of the first embodiment, thereby enabling a reduction in the angular error associated with the rotary magnetic field MF generated by the magnetic field generating unit having a simpler configuration.

The other configuration, operation and effects of the present embodiment are the same as those of the first embodiment.

Third Embodiment

Now, a third embodiment of the present invention will be described. 21 FIG. 12 is a circuit diagram illustrating a first example of a configuration of the detection unit of the third embodiment. FIG. The angle sensor system 1 according to the third embodiment differs from the first embodiment as follows.

At the angle sensor 2 of the angle sensor system 1 According to the present embodiment, the at least one first magnetic detection element included in the first detection signal generation unit 11 or at least one second magnetic detection element included in the second detection signal generation unit 12 is included, a magnetic layer provided with a third magnetic anisotropy. The magnetic layer provided with the third magnetic anisotropy is a layer whose direction of magnetization varies according to the direction DM of the rotating magnetic field at the detection position PR. The third magnetic anisotropy is, for example, a magnetic shape anisotropy.

According to the present embodiment, in the one of the at least one first magnetic detection element and the at least one second magnetic detection element, the first or second magnetic layer is provided with the third magnetic anisotropy, in addition to the first or second magnetic anisotropy. The details of the first to third magnetic anisotropies are the same as those of the second embodiment.

In the present embodiment, the angle detection unit is 20 of the second embodiment shown in FIG 19 , instead of the angle detection unit 20 of the first embodiment.

A first example of the configuration of the first and second detection signal generating units 11 and 12 will now be described in detail with reference to FIG 21 described. In the first example, each of the first magnetic detection elements R1, R2, R3, and R4 in the second detection signal generation unit 12 includes at least one MR element including a free layer provided with the second magnetic anisotropy. The free layer provided with the second magnetic anisotropy corresponds to the second magnetic layer. In the first example, the free layer serving as the second magnetic layer is provided with the third magnetic anisotropy in addition to the second magnetic anisotropy. 21 illustrates an exemplary shape of the second magnetic layer. The shaping of the second magnetic layer In a form having a first major axis parallel to the Y-direction and a second major axis parallel to the X-direction, that is generally a cross-shaped shape, the second magnetic layer provides the second magnetic anisotropy and the third magnetic anisotropy, which are both are magnetic form anisotropies. The simple axis direction established by the third magnetic anisotropy is in this case parallel to the X direction, as in the simple axis direction established by the first magnetic anisotropy.

Now, second to fourth examples of the configuration of the first and second detection signal generating units 11 and 12 will be described. In the second example, the at least one first magnetic detection element in the first detection signal generation unit 11 includes a magnetic layer provided with the first and third magnetic anisotropies. In this case, for example, the free layer of at least one of the one or more MR elements included in each of the magnetic detection elements R1, R2, R3, and R4 in the first detection signal generation unit 11 is provided with the first and third magnetic anisotropies, and the free layer of at least one of the one or more MR elements included in each of the magnetic detection elements R1, R2, R3 and R4 in the second detection signal generation unit 12 are included, is provided with only the second magnetic anisotropy. The simple axis direction established by the third magnetic anisotropy is in this case parallel to the Y direction, as in the simple axis direction established by the second magnetic anisotropy.

In the third and fourth examples, as in the 5 As shown in the first embodiment, the simple axis direction established by the first magnetic anisotropy is parallel to the Y direction, and the single axis direction established by the second magnetic anisotropy is parallel to the X direction.

In the third example, the at least one second magnetic detection element includes in the second detection signal generation unit 12 a magnetic layer provided with the second and third magnetic anisotropies. In this case, the simple axis direction established by the third magnetic anisotropy is parallel to the Y direction, as in the simple axis direction established by the first magnetic anisotropy.

In the fourth example, the at least one first magnetic detection element includes in the first detection signal generation unit 11 a magnetic layer provided with the first and third magnetic anisotropies. In this case, the simple axis direction established by the third magnetic anisotropy is parallel to the X direction, as in the simple axis direction established by the second magnetic anisotropy.

In view of the production accuracy of the MR elements and other factors, the simple axis direction in the above first to fourth examples may slightly deviate from the directions described above.

In the present embodiment, the second order magnetic field related angular error is corrected by using the third magnetic anisotropy and the first or second magnetic anisotropy. Like the second embodiment, the present embodiment eliminates the need for the correction processing unit 23 of the first embodiment, thereby enabling the reduction of the angle error associated with the rotating field MF generated by the magnetic field generating unit having a simpler configuration.

The other configuration, operation and effects of the present embodiment are the same as those of the first or second embodiment.

Fourth Embodiment

A fourth embodiment of the present invention will now be described with reference to FIGS 22 to 25 described. The 22 to 25 each show first to fourth states of the angle sensor system 1 according to the fourth embodiment.

The angle sensor system 1 according to the fourth embodiment differs from the first embodiment as follows. The magnetic field generating unit of the angle sensor system 1 according to the fourth embodiment is a magnet 8th that is different from the magnet 5 the first embodiment differs. The magnet 8th includes a plurality of pairs of N and S poles arranged alternately in the first direction. The first direction is the X direction.

In the 22 to 25 the X direction is to the right, the Y direction is up, and the Z direction is out of the plane of the drawing. The magnet 8th has a side surface 8a which is parallel to the X direction. In the present embodiment, the detection unit is 10 of the angle sensor 2 arranged such that they are the side surface 8a of the magnet 8th opposite. The 22 to 25 illustrate a variety of curves near the side surface 8a of the magnet 8th wherein the plurality of curves represent magnetic field lines.

Either the angle sensor 2 or the magnet 8th is linearly movable in the direction DL parallel to the first direction (X direction) in response to the movement of a moving body (not shown). In other words, the relative position of the magnet 8th with respect to the detection position PR in the first direction (X direction) variably. In the in 22 As shown, the direction DL is the X direction.

The reference plane in the present embodiment is perpendicular to the Z direction. When the relative position of the magnet 8th to the detection position PR in the direction DL, the direction DM of the rotating magnetic field MF is turned to 22 counterclockwise. The target angle θ and the rotational field angle θM are expressed in positive values as viewed from the reference direction DR in the counterclockwise direction, and expressed in negative values from the reference direction DR in the clockwise direction. The definitions of the first direction D1, the second direction D2, the first magnetic field component MF1 and the second magnetic field component MF2 are the same as those in the first embodiment.

The angle sensor 2 detects the rotating magnetic field MF at the detection position PR and generates the detection angle value θs with a correspondence to the target angle θ. In the present embodiment, the target angle θ is an angle representing the relative position of the magnet 8 with respect to the detection position PR, wherein a pitch of the magnet 8th 360 °.

In the in 22 1, the detection position PR is in an imaginary plane including the boundary between adjacent N and S poles of the magnet 8. In the first state, the target angle θ is 0 °.

The in 23 shown second state is a state in which the magnet 8th was moved by ¼ pitch from the first state in the direction DL. In the second state, the target angle θ is 90 °.

The in 24 shown third state is a state in which the magnet 8th relative to the second state was moved by ¼ pitch in the direction DL. In the third state, the target angle θ is 180 °.

The in 25 shown fourth state is a state in which the magnet 8th relative to the third state was moved by ¼ pitch in the direction DL. In the fourth state, the target angle θ is equal to 270 °.

A movement of the magnet 8th by ¼ pitch compared to the fourth state in the direction DL leads to the in 22 shown first state.

In the present embodiment, when the target angle θ varies with a predetermined period, the first magnetic field component MF1 and the second magnetic field component MF2 of the rotary magnetic field MF include the ideal magnetic field component, the third harmonic magnetic field component, and the fifth harmonic magnetic field component, respectively, as in the first embodiment.

The angle sensor 2 According to the present embodiment may have the same configuration as that in the first embodiment, the second embodiment, or the third embodiment.

The remaining configuration, function and effects of the present invention are the same as in any one of the first to third embodiments.

The present invention is not limited to the aforementioned embodiments, and various modifications can be made. For example, in the present invention, the magnetic detection elements are not limited to spin valve MR elements (GMR and TMR elements) or ARM elements, and may be any magnetic detection elements having a magnetic layer whose magnetization direction corresponds to the direction of a rotating magnetic field varied. For example, Hall elements each including a ferromagnetic layer and utilizing ferromagnetic Hall effects may be used as the magnetic detection elements.

The magnetic anisotropy provided to the magnetic layer is not limited to a magnetic shape anisotropy and may be a magnetocrystalline anisotropy or a stress-induced magnetic anisotropy.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be embodied in other embodiments than the foregoing particularly preferred embodiments.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2011 [0003]
• JP 158488 A [0003]
• JP 2011158488 A [0008, 0009]

Claims (15)

An angle sensor system (1) comprising: a magnetic field generating unit for generating a rotating magnetic field whose direction varies at a predetermined detection position according to an angle to be detected; and an angle sensor (2) for detecting the rotating magnetic field at the detection position and generating a detection angle value corresponding to the angle to be detected, characterized in that: the rotary magnetic field at the detection position has a first magnetic field component in a first direction and a second magnetic field component in a second one Direction orthogonal to the first direction, the angle sensor (2) comprises: a first detection signal generating unit (11; 111) for generating a first detection signal having a correspondence to the cosine of an angle which is the direction of the rotating magnetic field at the detection position the first direction forms; a second detection signal generating unit (12; 112) for generating a second detection signal having a correspondence to the sine of the angle which the direction of the rotating magnetic field forms at the detection position with respect to the first direction; and an angle detection unit (20) for generating the detection angle value on the basis of the first and second detection signals, the first detection signal generating unit (11; 111) comprises at least a first magnetic detection element, the at least one first magnetic detection element comprises a first magnetic layer, the magnetization direction thereof according to the direction of the rotary magnetic field at the detection position, the first magnetic layer is provided with a first magnetic anisotropy, the second detection signal generating unit (12; 112) comprises at least one second magnetic detection element, the at least one second magnetic detection element comprises a second magnetic layer, the magnetization direction thereof according to the direction of the rotary magnetic field at the detection position varies, the second magnetic layer is provided with a second magnetic anisotropy, when the angle to be detected varies with a predetermined period, the first and second Magnetfe each of the ideal magnetic field components periodically varies to form an ideal sinusoidal curve, and the fifth harmonic magnetic field component is an error component corresponding to a fifth harmonic of the ideal magnetic field component, the fifth harmonic magnetic field component causes an error that varies in the detection angle value with ¼ of the predetermined period, assuming that each of the first and second magnetic field components consists only of the ideal magnetic field component when the angle to be detected varies with the predetermined period, the first and second detection signals each have an ideal signal component and include a third harmonic signal component, wherein the ideal signal component periodically varies to map an ideal sinusoidal curve, and the signal component of the dr In the second harmonic, an error component that corresponds to a third harmonic of the ideal signal component, the third harmonic signal component results from the first and second magnetic anisotropies, causes an error that varies in the detection angle value with ¼ of the predetermined period, and the first and second magnetic Anisotropies are set to allow the detection angle value to contain a reduced error that varies with ¼ the predetermined period compared to both the error caused only by the magnetic field component of the fifth harmonic in the detection angle value, and the error that only the Caused signal component of the third harmonic in the detection angle value. Angle sensor system (1) to Claim 1 wherein the error caused only by the fifth harmonic magnetic field component in the detection angle value and the error caused only by the third harmonic signal component in the detection angle value have a phase difference of 45 °. Angle sensor system (1) to Claim 1 or 2 wherein both the first and second magnetic anisotropies are magnetic shape anisotropies. Angle sensor system (1) according to one of Claims 1 to 3 wherein a single axis direction established by the first magnetic anisotropy and a single axis direction established by the second magnetic anisotropy are orthogonal to each other. Angle sensor system (1) according to one of Claims 1 to 4 wherein when the angle to be detected varies with the predetermined period, each of the first and second magnetic field components further includes a third harmonic magnetic field component, wherein the magnetic field component is the third harmonic is an error component corresponding to a third harmonic of the ideal magnetic field component, the third harmonic magnetic field component causes an error that varies in the detection angle value by ½ of the predetermined period, and the angle sensor (2) corrects the error that the third harmonic magnetic field component in the Detection angle value caused. Angle sensor system (1) to Claim 5 wherein the angle detection unit performs correction processing to correct the error caused by the third harmonic magnetic field component in the detection angle value. Angle sensor system (1) to Claim 6 wherein the correction processing comprises performing a conversion calculation to convert the first and second detection signals into first and second calculation signals to be used for the angle calculation for calculating the detection angle value, and the conversion calculation converts the first and second detection signals into the first and second calculation signals; to allow the detection angle value to include a reduced error that varies with ½ of the predetermined period compared to the case of calculating the detection angle value using the first and second detection signals in the angle calculation. Angle sensor system (1) to Claim 5 wherein one of the at least one first magnetic detection element and the at least one second magnetic detection element comprises a magnetic layer provided with a third magnetic anisotropy, the magnetic layer provided with the third magnetic anisotropy being a layer whose direction of magnetization is in the direction of the rotating magnetic field varies at the detection position, and the error caused by the third harmonic magnetic field component in the detection angle value is corrected by the first or second magnetic anisotropy in the other of the at least one first magnetic detection element and the at least one second magnetic detection element and the third magnetic anisotropy , Angle sensor system (1) to Claim 8 wherein the third magnetic anisotropy is a magnetic shape anisotropy. Angle sensor system (1) to Claim 8 or 9 wherein in the one of the at least one first magnetic detection element and the at least one second magnetic detection element, the magnetic layer provided with the third magnetic anisotropy is other than the first or second magnetic layer. Angle sensor system (1) to Claim 8 or 9 wherein, in which one of the at least one first magnetic detection element and the at least one second magnetic detection element, the first or second magnetic layer is provided with the third magnetic anisotropy in addition to the first and second magnetic anisotropy, respectively. Angle sensor system (1) according to one of Claims 8 to 11 wherein the third magnetic anisotropy and the first or second magnetic anisotropy used to correct the error causing the third harmonic magnetic field component in the detection angle value justify the same single axis direction. Angle sensor system (1) according to one of Claims 1 to 12 wherein the at least one first magnetic detection element and the at least one second magnetic detection element each comprise one or more magnetoresistive elements. Angle sensor system (1) according to one of Claims 1 to 13 wherein the magnetic field generating unit is a magnet (5) which is rotatable about a center axis, the detection position is outside the center axis, and the angle to be detected corresponds to a rotational position of the magnet (5). Angle sensor system (1) according to one of Claims 1 to 13 wherein the magnetic field generating unit is a magnet (8) comprising a plurality of pairs of N and S poles arranged alternately in the first direction, a relative position of the magnet (8) with respect to the detection position in the first direction is variable , and the angle to be detected is an angle representing the relative position of the magnet (8) with respect to the detection position, wherein a pitch of the magnet (8) is 360 °.

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